How Does Light Behave Inside a Black Hole?

Click For Summary

Discussion Overview

The discussion centers on the behavior of light within a black hole, specifically addressing why light cannot escape once it crosses the Schwarzschild radius. Participants explore concepts related to spacetime curvature, energy changes, and the implications of redshift and blueshift for photons near and within the event horizon.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Giuliano questions whether photons impact the superdense mass of the black hole or if they cannot escape due to insufficient energy to overcome spacetime curvature.
  • One participant asserts that light entering a black hole cannot escape and contributes to the black hole's mass.
  • There is a discussion about the wavelength of light being lengthened as it approaches the black hole, with some participants suggesting that this indicates a loss of energy.
  • Another participant clarifies that while light is blue-shifted as it approaches the black hole, it does not lose energy to the point of becoming zero.
  • There is a mention of a photon born at the event horizon experiencing infinite redshift, leading to a discussion on the implications of this for observers outside the black hole.
  • One participant questions the meaningfulness of discussing redshift for photons that cannot reach an observer outside the event horizon.
  • Another participant suggests that the redshift and wavelength stretching can be attributed to the inability of light to escape from a black hole.

Areas of Agreement / Disagreement

Participants express varying views on the implications of redshift and blueshift for light near a black hole, with no consensus reached on the interpretation of energy changes or the fate of photons at the event horizon.

Contextual Notes

Participants reference concepts such as the Schwarzschild radius, blueshift, and redshift without fully resolving the implications of these phenomena on the behavior of light within a black hole.

Giuliano97
Messages
6
Reaction score
0
Good morning everyone, I'm Giuliano and I would like to know how light behaves in a black hole and because it can not get out.
More precisely, i understand that light moves in curved space-time format from the black hole, but once passed within swarzchild radius the photon is expected to impact the superdense mass of the black hole , or can not get out because it does not have enough energy to climb the spacetime curvature and ends up to " stretch " within he has no more energy.
sorry for my ignorance and for my english and thanks in advance.
 
Physics news on Phys.org
If a light beam goes into a black hole it can never go out.What happens to it.The photon energy increases the mass of black hole.Every energy fallen into blak hole makes it heavier.
 
Giuliano97 said:
i understand that light moves in curved space-time format from the black hole
yes
but once passed within swarzchild radius the photon is expected to impact the superdense mass of the black hole
yes
, or can not get out because it does not have enough energy to climb the spacetime curvature
yes
and ends up to " stretch " within he has no more energy.
Don't understand what you mean here.
 
@phinds
i mean that its wavelength would be lengthened
 
Giuliano97 said:
@phinds
i mean that its wavelength would be lengthened
Giuliano97 said:
@phinds
i mean that its wavelength would be lengthened
OK, but what's with the "no more energy" ?

As a beam of light approaches a black hole, it becomes blue shifted from the point of view of someone closer to the black hole and I suppose that process continues past the event horizon, but I don't see the energy going to zero.
 
@phinds
thank you for your answer,
As i know photons becomes blue shifted when they enter in the black hole and a red shift when they try to escape from it .
A photon that was born exactly on the horizon of events , directed towards the outside of the black hole , would suffer an infinite red shift so its wavelength would be lengthened to infinite (his energy would become zero ) .
Sorry for my english again..
 
@Nugatory
I agree, but although we can not see the actual redshift of light , we can still take the redshift and the stretching of the wavelength as due to lack of leakage of light from a black hole ?
 

Similar threads

  • · Replies 22 ·
Replies
22
Views
2K
  • · Replies 31 ·
2
Replies
31
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 67 ·
3
Replies
67
Views
6K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 63 ·
3
Replies
63
Views
6K
  • · Replies 16 ·
Replies
16
Views
2K